Surface properties of medical devices touch upon a whole host of issues, including mechanical performance and biocompatibility, among many others. For example, during a typical balloon angioplasty procedure, a stent is crimped upon a balloon and advanced into the vasculature of a patient. The stent is subsequently expanded upon balloon inflation to engage the walls of a blood vessel, thereby providing patency to the vessel. In general, the lower the surface energy of the stent, the greater the ease of balloon withdrawal after the stent is expanded. Because they are hydrophobic, however, devices having low surface energies are not necessarily desirable from a biocompatibility standpoint.
The in vivo delivery of a biologically active agent within the body of a patient is common in the practice of modern medicine. In vivo delivery of biologically active agents is often implemented using medical devices that may be temporarily or permanently placed at a target site within the body. These medical devices can be maintained, as required, at their target sites for short or prolonged periods of time, delivering biologically active agents at the target site. For example, drug delivery from stents for the treatment of restenosis is widely accepted. Commercially available drug eluting coronary stents include those available from Boston Scientific Corp. (TAXUS), Johnson & Johnson (CYPHER), and others. Unfortunately, only a few products have been successful to date, in part, due to the inability to create products with effective and safe dose and release kinetics. For coronary stents with polymeric drug-eluting coatings, dose and release kinetics may be affected, for example, by the physiochemical properties of the drug and the polymeric carrier, by the interactions between the drug and carrier, and by the geometry of the system.